There is a display application in the electrical switch protection circuit. When the circuit system fails, the display can indicate the type of the failure, and this indication state can be maintained in a power-off state, that is, the display can maintain the displayed pattern in the case when there is no power supply. Such display is named as bistable display. The entire display plane of the bistable display is treated as a pixel with being led out by two electrodes, and in this way it can be used as a bistable indicator light. Since it does not require power to maintain the indication, it is of high utility in electrical switch indications. As a functional extension of such display, we can print a pattern on the display, and a bistable indicator light with specific indication significance can be made out.
In order to make the bistable display display a specific pattern, currently there are two realization methods. The first one is to print a pattern on the surface of the display. As shown in FIG. 1(a), the color of the pattern is the same as the background color in the dark state of the display. The printed pattern can be thereby displayed when the display is in the bright state (the first stable state of the display). Its disadvantage is that since the bistable display has certain optical reflections in the dark state (the second stable state of the display), the actual effect of the printed pattern cannot be completely consistent with the background color of the display in the dark state, resulting in that the display can vaguely show the printed pattern even in a dark state and that the printed pattern has reliability risks such as breakage, peeling or the like. The second method is to lead out a separate pattern electrode in the display which composes, together with background electrode and display common electrode, a three-electrode input driving way, as shown in FIG. 1(b). Its disadvantage is that although it can improve the display effect of the pattern, due to one additional set of driver circuits, it is incompatible with the previous driver circuits and increases the cost of the driver circuits.